Browsing by Author "Reiff, Patricia"

Now showing 1 - 6 of 6
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    Improvements in short-term forecasting of geomagnetic activity
    (American Geophysical Union, 2012) Bala, Ramkumar; Reiff, Patricia
    We have improved our space weather forecasting algorithms to now predict Dst and AE in addition to Kp for up to 6 h of forecast times. These predictions can be accessed in real time at http://mms.rice. edu/realtime/forecast.html. In addition, in the event of an ongoing or imminent activity, e-mail “alerts” based on key discriminator levels have been going out to our subscribers since October 2003. The neural network–based algorithms utilize ACE data to generate full 1, 3, and 6 h ahead predictions of these indices from the Boyle index, an empirical approximation that estimates the Earth’s polar cap potential using solar wind parameters. Our models yield correlation coefficients of over 0.88, 0.86, and 0.83 for 1 h predictions of Kp, Dst, and AE, respectively, and 0.86, 0.84, and 0.80 when predicting the same but 3 h ahead. Our 6 h ahead predictions, however, have slightly higher uncertainties. Furthermore, the paper also tests other solar wind functions—the Newell driver, the Borovsky control function, and adding solar wind pressure term to the Boyle index—for their ability to predict geomagnetic activity.
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    MMS Observations of Secondary Reconnection X-Lines and the Unexpected Phenomena Surrounding Them
    (2023-04-19) Marshall, Andrew; Reiff, Patricia
    Magnetic reconnection, the process that explosively converts energy from magnetic fields into particle thermal energy and kinetic energy, plays an important role both on the dayside an on the nightside of Earth’s magnetosphere. During periods when the interplanetary magnetic field (IMF) is southward, reconnection will occur near the subsolar point on Earth’s dayside and the neutral line on the nightside. In this work, we present one nightside event where we observed, for the first time, reconnection as part of an earthward-propagating dipolarization front (DF). Previous studies have shown current sheets in such events but never reconnection. In the second event, we discuss a dayside event with unusual wave activity in the reconnection current layer. The x-line observed in this event appears to be a secondary x-line that is moving southward while also seeing a lower hybrid drift wave (LHDW) and energy conversion due to the parallel electric field. This is the first time such wave activity has been observed at an x-line, and the energy conversion is not due to the component of the electric field that normally contributes to it. We use in-situ measurements from the magnetospheric multiscale (MMS) spacecraft, which is the first mission able to provide multipoint measurements of plasma and fields at a time resolution fast enough to observe the electron diffusion region (EDR) of reconnection. We compare these to the community coordinated modeling center (CCMC) global models of the magnetic field to help identify the expected positions of the reconnecting field lines and to determine the changes to the magnetosphere on one-minute timescales that would cause the dynamics observed at MMS’s location.
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    MMS Observations of Storm-Time Magnetopause Boundary Layers in the Vicinity of the Southern Cusp
    (Wiley, 2022) Burkholder, Brandon L.; Chen, Li-Jen; Fuselier, Stephen; Gershman, Daniel; Schiff, Conrad; Shuster, Jason; Zou, Ying; Walsh, Brian M.; Reiff, Patricia; Petrinec, Steve; Sciola, Anthony
    During a storm-time interval around winter solstice, observations by the Magnetospheric Multi-Scale (MMS) Mission show multiple distinct magnetopause boundary layers (BLs) in the vicinity of the southern cusp. The microphysics of the solar wind-magnetosphere interaction during storm times are not well understood, because the observations are relatively lacking. This event enables the opportunity to probe the storm-time magnetopause, and observations support that MMS was near a reconnection site equatorward of the southern cusp, suggesting active reconnection in close proximity to closed magnetic flux regions in the BL. The Grid Agnostic magnetohydrodynamics (MHD) for Extended Research Applications global MHD simulation shows evidence for transient secondary reconnection sites near the southern cusp, demonstrating mechanisms to form closed field line regions of the BL.
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    Studies of Intermediates Created via Dissociative Electron Attachment through Heavy-Rydberg Ion-Pair State Formation in Rydberg Atom Collisions
    (2015-04-15) Buathong, Sitti; Dunning, F. Barry; Killian, Thomas; Reiff, Patricia
    The lifetimes and decay energetics of intermediates have been studied by measuring the velocity and angular distributions of heavy-Rydberg ion pair states formed through electron transfer in thermal-energy collisions between Rydberg atoms and attaching targets. The analysis of the experimental results by using Monte Carlo simulations indicates that electron attachment to CF3I and CH2Br2 forms very-short-lived intermediates whereas electron capture by CCl4 produces a long-lived intermediate.
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    Testing the estimated hypothetical response of a major CME impact on Earth and its implications to space weather
    (Wiley, 2015) Bala, Ramkumar; Reiff, Patricia; Russell, C.T.
    The high-speed coronal mass ejection (CME), ejected on 23 July 2012, observed by STEREO-A on the same day as the leading edge of the CME arrived at 1AU was unique both in respect to the observed plasma and magnetic structure and the large solar energetic particle flux that dynamically regulated the shock front. Because of its great intensity, it has been hailed as “Carrington 2” by some, warning that, had that CME been heading toward the Earth, it might have caused a major space weather event. We used the Rice Artificial Neural Network algorithms with the solar wind and interplanetary magnetic field parameters measured in situ by STEREO-A as inputs to infer what the “geoeffectiveness” of that storm might have been. We have also used an MHD model in Open Geospace General Circulation Model to understand the global magnetospheric process in time sequence. We presently show our neural network models of Kp and Dst on our real-time prediction site: http://mms.rice.edu/realtime/forecast.html. Running this event through our models showed that, in fact, this would have been an exceptional event. Our results show a prediction resulting in a Kp value of 8+, a Dst of nearly −250 nT, but when assumptions about maximum dipole angle tilt and density are made, predictions resulting in Kp of 11− and Dst dipping close to −700 nT are found. Finally, when solar energetic proton flux is included, the Kp and Dst predictions drop to 8− and ≈−625 nT, respectively.
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    Validating the Rice neural network and the Wing Kp real-time models
    (American Geophysical Union, 2014) Bala, Ramkumar; Reiff, Patricia
    The Rice neural network models of Kp have been running in real time at http://mms.rice.edu/realtime/forecast.html since October 2007; Dst and AE models were added to our operations in May 2010. All these models use the Boyle index as basis functions computed from ACE real time inputs. Later, two more driving functions were included in November 2012: (a) the “Ram” functions that had dynamic pressure term added to the Boyle index and (b) the Newell functions. The Wing models are a set of neural network-based Kp forecast models adopted by NOAA/Space Weather Prediction Center in March 2011 to supersede the Costello Kp model. This study indicates that any of the three Rice neural net predictors had a better success rate than the Wing model in predicting Kp (r=0.828 with Boyle, r=0.843 with Ram, and r=0.820 with Newell for 1 h predictions; similarly, r=0.739, 0.769, and 0.755 for 3 h predictions) in real time. In a head-to-head challenge using harvested real-time outputs between April 2011 and February 2013, the Rice Boyle Kp models predicted better than the Wing models (0.771 versus 0.714 for 1 h predictions and 0.770 versus 0.744 for 3 h predictions). In addition, Wing’s prediction was missing more often than the Rice prediction (≈6% versus 4.6%), meaning it had less reliability. The Rice models also predict AE (r=0.811 with Boyle; 0.806 with Ram; 0.765 with Newell, and 0.743 with Boyle; 0.747 with Ram for 1 h and 3 h predictions) and pressure-corrected Dst (r=0.790; 0.767, and 0.704, and r=0.795; 0.797 and 0.707 for 1 h and 3 h predictions).